Re: [CAD_CAM_EDM_DRO] OT! Air compression, reply off-list

No John...NO, NO, NO!!!
Don't try a homebrew rig for filling diving bottles.
BAD, BAD, BAD, BAD, BAD.
The problems are twofold:
First, the pressures involved are high enough to demand some well thought
out safeguards.
I'm not saying it can't be done, but the safety risks are high, and the
procedures even just for filling, never mind the pump engineering are quite
stringent for this class of pressure vessel.
Second, inspired air at pressures above atmospheric must be super
clean...lots of guys got killed finding that out in the forties and fifties.
One of the culprits associated with a number of fatalities turned out to be
traces of crankcase lubricating oil that partially decomposed at the
temperatures and pressures that these compressors run at.
The other big killer, of course turned out to be carbon monoxide from
setting up the air inlet too close to the gasoline engine exhaust.
Those little floating hookahs that used to be advertised in Popular Science
and elsewhere knocked off a fair number of weekend warriors this way, before
they were pulled from the shelves.
So please, do yourself a big favour...just go to the dive shop and pay for
some peace of mind!!!
Cheers

Marcus

----- Original Message -----
From: "John" <johnhe-uk@...>
To: <cad_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, July 27, 2002 9:37 AM
Subject: [CAD_CAM_EDM_DRO] OT! Air compression, reply off-list


[Please reply to me off list]

I apologise for this being off topic but I noticed a couple of you guys
seemed to understand what is required for a pump to achieve the high
pressures of a water jet table and some where interested in the idea of
machining a pump out. I am interested in how a high pressure air compressor
differs from a standard one you see on car spray guns etc. The type I mean
are the ones used for recompressing scuba air tanks. They achieve a pressure
up to around 3kpsi and I was wondering if there's a tiny possibility I could
machine such a 'lower' (compared to water jet) pump head out myself.

I have been offered the opportunity to go scuba diving with some of my metal
working amigos from work but the gear is expensive and I'd like to be able
to recharge my own cylinders. If you like, this is a CNC project more than
problem as it'd probably go on some CNC machinery, like me lathe.

So, is it possible? What do the pumps look like inside? Do you have any
reference I could look at? It's got to be cheaper than buying them. They're
about £4k new and they aren't running at the monster pressures a water jet
table does.

Please reply off-list,
John H.
johnhe-uk@...


[Non-text portions of this message have been removed]


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